1. Field of the Invention
This invention relates to lithium secondary cells and more particularly, to a negative electrode adapted for use in lithium secondary cells and capable of suppressing macro-crystals of dendrite from growing during the course of charge and discharge cycles of the cell.
2. Description of the Prior Art
Recently, attention has been paid to lithium metal, which has the lowest potential and has a maximum energy density per unit weight and unit volume, for use as an active substance of a negative electrode in high energy density-oriented secondary cells. For instance, Japanese Laid-open Patent Application No. 2-139860 sets out lithium secondary cells.
With lithium secondary cells using a lithium metal as the negative electrode, the charge and discharge life thereof will become shortened. This is because dendrite crystals of lithium are undesirably produced owing to the dissolution and precipitation of the lithium metal during the course of charge and discharge cycles of the cell, so that the charge and discharge efficiencies at the negative electrode lower. Moreover, the dendrite crystals which are grown up to large sizes may break through a separator, with the attendant problem that the negative electrode electrically contact with the positive electrode, resulting in short-circuiting.